This invention relates generally to apparatus for supporting a person""s cranium, cervical, thoracic, and lumbar spin, including passenger safety apparatus for vehicles, and more specifically, relates to apparatus for preventing whiplash related and similar injuries.
Whiplash related injuries are caused by the rapid acceleration of a person""s cranium and cervical spin, which occurs, for example, in a rear end automobile collision. The rapid acceleration causes the extension and flexion of the cervical spine which, in turn, can cause severe injury. Types of whiplash related injuries include fractured and/or dislocated vertebrae, torn ligaments (both anterior and posterior of the spinal column), and avulsion of parts of the vertebrae, ligaments and in vertebrae discs. Similar injuries can occur to the thoracic and lumbar spinal areas.
It has thus been found, for example, that the C4, C5 and C6 cervical vertebrae, and the paravertebrae ligaments are most often damaged with whiplash related injuries, although the entire cervical as well as the thoracic and lumbar spine may well be involved. Rapid hypertension of the cervical spin can thus stretch the anterior longitudinal ligament, thus placing it in traction and causing either bone or ligamentous damage. Such hyperextension typically damages the C1 through C7 cervical vertebrae. The vertebral artery, which extends through an opening in the vertebrae, and the sympathetic nerve fibers that surround the artery are also often damaged. These types of injuries cause severe disabilities and, in some instances, death.
Seatbacks and/or headrests in automobiles, trucks, and other types of vehicles are provided to prevent whiplash related injuries to passengers during collisions, but typically fail. During a rear-end vehicle collision, the forces of the collision typically cause a passenger""s cranium and cervical spin to rapidly accelerate toward the rear of the vehicle. Once the cranium strikes the seatback or headrest, it then rapidly accelerates in the opposite direction toward the front of the vehicle. The rearward acceleration of the cranium, and resulting collision with the seatback or headrest, causes hyperextension of the cervical spin and, thus typically injures the anterior structure of the passenger""s neck. The forward acceleration of the cranium, on the other hand, causes hyperflexion of the cervical spin and typically injures the posterior structure of the neck.
One problem with known seatbacks and/or headrests is that the surface intended to stop the movement of a person""s head and neck is typically flat, or does not correspond to the posterior contour thereof. As a result, during a rear-end collision, typically the back, or posterior portion of the cranium is the first portion of the passenger""s body to strike the seatback or headrest. However, the cervical spine, which is located inferiorly with respect to the posterior portion of the cranium, continues to move toward the headrest. As a result the cervical spine is forced to move relative to the cranium which, in turn, causes severe vertebral damage.
Also, the top surfaces of many known headrests are located at about the same height, or below the height of a passenger""s ears, which is normally about the center of gravity of the head. When a passenger""s cranium is forced against such a headrest during a collision, it often slides upwardly over the top edge of the headrest. As a result, the cranium is stretched upwardly relative to the cervical spine typically causing further vertebral damage.
In my issued U.S. Pat. Nos. 5,181,763 and 5,290,091, the entire disclosures of which are hereby incorporated by reference, apparatus is disclosed for preventing whiplash-related injuries to a passenger in a vehicle. In one embodiment of these inventions, the apparatus comprises a frame supported on a seat of the vehicle and located behind the cranium and cervical spin of a passenger on the seat. A layer of resilient material defining a supporting means is located behind the cranium and cervical spine of the passenger and defines one or more contours that interfit with the posterior contour of the passenger""s cranium and cervical spine. The supporting means includes a first surface located behind the passenger""s cranium and projecting upwardly above the approximate center of mass of the passenger""s cranium and having a substantially flat portion including a cranium contact zone for contacting and supporting the approximate central posterior are of the passenger""s cranium; and a second surface located below the first surface and defining a substantially convex smooth curve, the maximum protrusion point of which projects anteriorly relative to the flat portion of the first surface. The second surface thereby contacts and supports the posterior portion of the passenger""s cervical spine substantially simultaneously with the contact of the passenger""s cranium with the first surface, thereby substantially simultaneously decelerating the cranium and cervical spine during a vehicle collision to prevent whiplash-related injuries to the passenger.
In such prior invention, the second surface is smoothly joined to the first surfaces by a transition surface which extends anteriorly at an obtuse angle from the first surface and is located to support the passenger""s posterior area approximately where the cranium meets the cervical spine.
A support member is coupled to the frame and supported on the seat, the support member being vertically moveable relative to the seat to adjust the position of the apparatus relative to the passenger and, thus, adjust the position of the supporting means to correspond to the posterior contour of the passenger""s cranium and cervical spine.
The frame can define a hollow enclosure and the layer of resilient material may consist essentially of a urethane foam which is molded thereon.
In a further embodiment of my prior apparatus, the first and second surfaces are defined at mutually spaced first and second support bodies, and the apparatus further includes means for vertically and horizontally displacing the first and second surfaces to adjust the position of same to accurately interfit with the posterior contour of different passengers. The first and second support bodies can be coupled to the frame and rendered movable by rack and pinion or equivalent means to enable desired vertical and/or horizontal displacements of same.
In my further U.S. Pat. No. 5,580,124, important modifications and improvements have been made in the aforementioned prior art apparatus to thereby provide yet further improved apparatus for preventing whiplash-related injuries to a passenger in a vehicle. In accordance with such invention, a vehicle-installed supporting seat for the passenger is provided, which includes a seat back provided with an integral head-neck restraint comprising a cranium support portion and a cervical spine support portion. Each said portion includes a layer of resilient material supported on an underlying inflexible support shell, which together act to effectively define a contour that interfits with the posterior contour of the passenger""s cranium and cervical spine. This contour thus presents a first surface located behind the passenger""s cranium for contacting the approximate center of mass of the cranium and supporting the approximate central posterior area of the passenger""s cranium, and a second surface located below the first surface and defining a substantially convex smooth curve, the maximum protrusion point of which projects anteriorly relative to where the first surface contacts the center of mass of the passenger""s cranium, the said second surface thereby contacting and supporting the posterior portion of the passenger""s cervical spine substantially simultaneously with the said contact of the passenger""s cranium with said first surface. The support shell is rearwardly displaceable upon being subjected to impressed forces generated from the passenger pressing against the restraint as a result of a rear end impact at said vehicle. A controllably deformable energy absorbing crush zone is disposed to the rear of the shell as to be compressed by the rearward displacement of the shell. The interfitting contour and thereby the inflexible shell, upon being displaced by said forces toward the underlying crush zone, retain the shape of the contour, whereby the cervical and cranium support portions act to substantially simultaneously decelerate the cranium and cervical spine of the passenger during a vehicle rear end impact, while the controlled deformation of the crush zone absorbs energy, to prevent whiplash-related injuries to the passenger.
The second surface of said contour is smoothly joined to said first surface by a transition surface of said contour, which extends anteriorly at an obtuse angle from said first surface, and which is located to support the passenger""s posterior area approximately where the cranium meets the cervical spine. The maximum protrusion point of said second surface projects anteriorly relative to said flat portion of said first surface a distance of 1 to 6 inches, and the maximum protrusion point is from 3 to 9 inches below the cranium contact zone.
The apparatus of the U.S. Pat. No. 5,580,124 invention preferably further includes a thoracic and lumbar spine support portion which are defined by downward extension of the support shell, resilient material and contour; whereby the thoracic and lumbar spine portion of the passenger are decelerated with the cranium and cervical spine during a rear end impact.
The crush zone may comprise one or more air bladders, and valve means responsive to rear end vehicular impact to enable the one or more bladders to at least partially deflate. The inflexible shell can, for example, be linked to one or more mechanical actuators which open the valves upon a predetermined displacement of the shell; or one or more sensors can upon detecting a rear end impact, actuate the valves to enable controlled deflation of the air bladders.
Similarly, one or more rear impact sensors can enable control signals upon an impact of sufficient magnitude, which signal disables a restraint means, e.g. by releasing a mechanical stop which otherwise prevents displacement of the inflexible shell (or of a plate linked to the shell) against or into the crush zone.
The crush zone can also comprise an impact collapsible cellular structure, such as a frangible foam. In still a further aspect, the crush zone may comprise an elastically deformable material which absorbs energy at a substantially more rapid rate than it releases same.
The crush zone may be sandwiched between the inflexible shell and a spaced fixed, rigid plate; or the crush zone can be spaced from the rear of the shell and contacted and compressed by an intermediate plate which is linked for displacement with the shell. Rearward displacement of the shell may be resisted by restraining means adapted to collapse at a preset strain.
Now in accordance with the present invention it has been found that by use of one or more inflatable air bladders having high strength exterior walls or skins, the desired specific configurations required for head and neck supports in accordance with the applicant""s prior patents may be constructed using the air bladder or bladders proper as the direct support for the resilient external portions of the supports which engage with the passenger""s head and neck. More specifically, the said bladders are provided with preformed surfaces such that when inflated the desired support shape is achieved at the portion of the bladder which faces the passenger. The bladder when properly inflated provides a sufficiently rigid curved surface that a further rigid backing plate conforming to the desired passengerxe2x80x94interfitting curve is not required. Since the bladder further is constructed of a expandable material such as a tough natural or synthetic rubber or polymer, at least some variation in the total expansion of the bladder is possible as well as some variation in the firmness in same, i.e., by varying the air pressure applied within the bladder interior. The bladder in turn supports the flexible covering of a natural or synthetic foam or the like which is relatively soft to provide comfort for the passenger. The fact that the bladder interior dimensions may be somewhat enlarged or diminished while yet retaining the basic external shape of its passenger adjacent face enables the passenger support in turn to achieve a degree of variation in its total perimeter dimensions to enable accommodation of passengers of differing sizes and having some variation in the location of curved head, neck and other surfaces to be supported.